A 0.2181 g sample of KHP required 17.29 mL of sodium hydroxide solution to reach the phenolphthalein end point. Calculate the molarity(M) of the NaOH solution.

mols KHP = grams/molar mass = ?

mols NaOH = mols KHP
M NaOH = mols NaOH/L NaOH.

To calculate the molarity of the NaOH solution, we need to use the equation:

Molarity (M) = (moles of solute) / (volume of solution in liters)

First, let's determine the moles of solute (KHP) used in the reaction:

1. Calculate the molar mass of KHP (potassium hydrogen phthalate):
- The molecular formula of KHP is C8H5KO4.
- Look up the atomic masses of carbon (C), hydrogen (H), potassium (K), and oxygen (O) from the periodic table.
- C: 12.01 g/mol, H: 1.008 g/mol, K: 39.10 g/mol, O: 16.00 g/mol.
- Calculate the molar mass:
(8 * 12.01) + (5 * 1.008) + 39.10 + (4 * 16.00) = 204.23 g/mol

2. Convert the mass of KHP to moles:
- Given mass = 0.2181 g.
- Moles = mass / molar mass = 0.2181 g / 204.23 g/mol.

Now, let's calculate the volume of NaOH solution in liters:

1. Convert milliliters (mL) to liters (L):
- Given volume = 17.29 mL.
- Volume in liters = 17.29 mL / 1000 mL/L.

Finally, we can calculate the molarity (M) of the NaOH solution:

Molarity (M) = Moles of solute / Volume of solution in liters.

Substitute the values:

Molarity (M) = (0.2181 g / 204.23 g/mol) / (17.29 mL / 1000 mL/L).

Calculate the result to find the molarity of the NaOH solution.